The iPhone-dev team has announced the release of the Windows version of QuickPwn for jailbreaking your iPhone or iPod Touch.
The tool supports OS 2.1 and provides unlocking and jailbreaking of first generation iPhones. It also supports jailbreaking of the first generation iPod Touch and the iPhone 3G. It does not support unlocking of the iPhone 3G or jailbreaking of second generation (n72ap based) iPod Touch.
Read more about it here.